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Biomedical subjects

John J Chen

Publications and source records attributed to John J Chen.

At least 19 recordsLinked to original sources
PubMed2006

Mice lacking the VIP gene show airway hyperresponsiveness and airway inflammation, partially reversible by VIP.

The mechanisms leading to asthma, and those guarding against it, are yet to be fully defined. The neuropeptide VIP is a cotransmitter, together with nitric oxide (NO), of airway relaxation, and a modulator of immune and inflammatory responses. NO-storing molecules in the lung were recently shown to modulate airway reactivity and were proposed to have a protective role against the disease. We report here that mice with targeted deletion of the VIP gene spontaneously exhibit airway hyperresponsiveness to the cholinergic agonist methacholine as well as peribronchiolar and perivascular cellular infiltrates and increased levels of inflammatory cytokines in bronchoalveolar lavage fluid. Immunologic sensitization and challenge with ovalbumin generally enhanced the airway hyperresponsiveness and airway inflammation in all mice. Intraperitoneal administration of VIP over a 2-wk period in knockout mice virtually eliminated the airway hyperresponsiveness and reduced the airway inflammation in previously sensitized and challenged mice. The findings suggest that 1) VIP may be an important component of endogenous anti-asthma mechanisms, 2) deficiency of the VIP gene may predispose to asthma pathogenesis, and 3) treatment with VIP or a suitable agonist may offer potentially effective replacement therapy for this disease.

Animals↗
PubMed2006

Removal of lead contaminated dusts from hard surfaces.

Government guidelines have widely recommended trisodium phosphate (TSP) or "lead-specific" cleaning detergents for removal of lead-contaminated dust (LCD) from hard surfaces, such as floors and window areas. The purpose of this study was to determine if low-phosphate, non-lead-specific cleaners could be used to efficiently remove LCD from 3 types of surfaces (vinyl flooring, wood, and wallpaper). Laboratory methods were developed and validated for simulating the doping, embedding, and sponge cleaning of the 3 surface types with 4 categories of cleaners: lead-specific detergents, nonionic cleaners, anionic cleaners, and trisodium phosphate (TSP). Vinyl flooring and wood were worn using artificial means. Materials were ashed, followed by ultrasound extraction, and anodic stripping voltammetry (ASV). One-way analysis of variance approach was used to evaluate the surface and detergent effects. Surface type was found to be a significant factor in removal of lead (p < 0.001). Vinyl flooring cleaned better than wallpaper by over 14% and wood cleaned better than wallpaper by 13%. There was no difference between the cleaning action of vinyl flooring and wood. No evidence was found to support the use of TSP or lead-specific detergents over all-purpose cleaning detergents for removal of lead-contaminated dusts. No-phosphate, non-lead-specific detergents are effective in sponge cleaning of lead-contaminated hard surfaces and childhood lead prevention programs should consider recommending all-purpose household detergents for removal of lead-contaminated dust after appropriate vacuuming.

Detergents↗
PubMed2006

Effect of quality improvement organization activities on outpatient diabetes care in eastern New York State.

BACKGROUND: Quality improvement organizations (QIOs) are contracted to improve the quality of care delivered to Medicare beneficiaries. The purpose of this study was to determine whether provider participation in New York State QIO activities resulted in significant improvements in the quality of diabetes care during the recent contract cycle with the Centers for Medicare & Medicaid Services. RESEARCH DESIGN: A retrospective analysis between participating and nonparticipating providers on their performance in 3 quality measures (biennial ophthalmology examination, biennial lipid profile monitoring, annual hemoglobin A1c monitoring) was used. Data of New York State Medicare beneficiaries before and after QIO intervention activities were examined to determine change in performance. General linear models were created to examine the effect QIO participation had on the change in performance for each measure. RESULTS: Providers who participated in QIO activities had significant absolute improvements in lipid monitoring compared with nonparticipating providers at high baseline performance for low (3.10%, P < 0.001), medium (2.57%, P < 0.001), and high (1.51%, P = 0.002) baseline patient volume, and medium baseline performance for low (2.38%, P < 0.001), and medium (1.85%, P < 0.001) baseline patient volume. The same trend was seen for hemoglobin A1c monitoring (4.28%, P < 0.001; 3.57%, P < 0.001; 2.15%, P < 0.001; 2.63%, P = 0.001; 1.92%, P = 0.006). For ophthalmology examination, participation resulted in significant changes at low (2.28%, P = 0.003) and medium (1.73%, P = 0.009) baseline patient volume. CONCLUSION: The study results suggest QIO activities can improve outpatient diabetes care; however, limitations in the study design preclude any definitive remarks.

Ambulatory Care↗
PubMed2006

Assessing the effects of racemic and single-enantiomer albuterol on airway secretions in long-term intubated patients.

OBJECTIVE: In vitro data suggest that the S-enantiomer of albuterol can induce mucociliary dysfunction. This clinical study assesses the clinical significance of standard doses of the S-enantiomer on airway secretions in long-term intubated patients by comparing a racemic formulation of albuterol, an R-enantiomer formulation, and normal saline solution. DESIGN: A placebo-controlled crossover study. PATIENTS: Fourteen stable intubated patients with a median duration of intubation of 21 months and a median age of 72 years. SETTING: Long-term ventilator unit in skilled nursing facility. INTERVENTIONS: Following a 2-week washout period during which regularly scheduled beta2-agonists were discontinued, tracheal aspirates were collected for 4 h/d for a 5-day period to establish baseline values, and the patients were then randomized in crossover manner to each of three nebulized treatments: normal saline solution, racemic albuterol, and R-albuterol. Each treatment was administered three times daily for 5 days, followed by a 2-day washout. MEASUREMENTS: Tracheal aspirates were analyzed for volume, sodium, chloride, bicarbonate, interleukin (IL)-8, IL-1beta, soluble intercellular adhesion molecule, and tumor necrosis factor-alpha. RESULTS: There were no consistent significant differences among the three treatment periods either in terms of volume of secretions or in the concentrations of the electrolytes or the inflammatory indexes. However, all three treatments, including saline solution, were associated with increased secretion volume after the first dose, but this effect was not apparent on subsequent doses. CONCLUSION: There were no significant differences between racemic albuterol and R-albuterol observed in this study for any of the parameters studied, suggesting that the S-enantiomer does not adversely affect airway secretions at recommended doses. In addition, the routine administration of nebulized beta(2)-sympathomimetic agonists to stable patients undergoing prolonged intubation, for the sole purpose of changing the volume and composition of secretions of airway secretions, is not supported by the results of this study.

Administration, Inhalation↗
PubMed2006

Amplitude and phase of cerebrospinal fluid pulsations: experimental studies and review of the literature.

OBJECT: A recently developed model of communicating hydrocephalus suggests that ventricular dilation may be related to the redistribution of pulsations in the cranium from the subarachnoid spaces (SASs) into the ventricles. Based on this model, the authors have developed a method for analyzing flow pulsatility in the brain by using the ratio of aqueductal to cervical subarachnoid stroke volume and the phase of cerebrospinal fluid (CSF) flow, which is obtained at multiple locations throughout the cranium, relative to the phase of arterial flow. METHODS: Flow data were collected in a group of 15 healthy volunteers by using a series of images acquired with cardiac-gated, phase-contrast magnetic resonance imaging. The stroke volume ratio was 5.1 +/- 1.8% (mean +/- standard deviation). The phase lag in the aqueduct was -52.5 +/-16.5 degrees and the phase lag in the prepontine cistern was -22.1 +/- 8.2 degrees. The flow phase at the level of C-2 was -5.1 +/- 10.5 degrees, which was consistent with flow synchronous with the arterial pulse. The subarachnoid phase lag ventral to the pons was shown to decrease progressively to zero at the craniocervical junction. Flow in the posterior cervical SAS preceded the anterior space flow. CONCLUSIONS: Under normal conditions, pulsatile ventricular CSF flow is a small fraction of the net pulsatile CSF flow in the cranium. A thorough review of the literature supports the view that modified intracranial compliance can lead to redistribution of pulsations and increased intraventricular pulsations. The phase of CSF flow may also reflect the local and global compliance of the brain.

Adult↗
PubMed2005

Hardy-Weinberg testing of a single homozygous genotype.

No proper statistical test is available for the evaluation of deviation of a single homozygous genotype from Hardy-Weinberg equilibrium (HWE) proportion. We propose a 1-d.f. chi2-test. The power of the proposed test is favorable compared to existing HWE testing procedures. The applications of this test are discussed.

Gene Frequency↗
PubMed2005

Voiding dysfunction: outcome in infants with congenital vesicoureteral reflux.

OBJECTIVES: To assess the rate of development of voiding dysfunction as an outcome in patients with congenital vesicoureteral reflux. METHODS: A computerized database was used to review the medical records of all patients with congenital reflux diagnosed before 6 months of age from 1988 to 2002. Only those infants with reflux who were followed up for at least 6 months past the age of toilet training were included. The parameters tabulated in this group included the presence of frequency, daytime wetting, urge incontinence, and infrequent voiding. The variables were summarized using contingency tables, and associations were evaluated using chi-square analysis and Fisher's exact test. RESULTS: Of 342 patients (145 boys and 197 girls) with reflux, 67 (19.6%) developed voiding dysfunction (17.9% boys and 20.8% girls). No statistically significant difference was found between high grade (IV and V) and low grade (I and II) or grade III reflux, or between unilateral and bilateral reflux for the development of voiding dysfunction. Of the patients with reflux who had renal damage on dimercaptosuccinic acid scan, 24.3% of girls and 30.4% of boys developed voiding dysfunction, which was not significantly different from those without renal damage. CONCLUSIONS: Approximately 20% of patients with vesicoureteral reflux diagnosed before 6 months of age demonstrated dysfunctional voiding after the age of toilet training. Voiding dysfunction occurred independent of sex, laterality, or severity of vesicoureteral reflux. Infants with renal damage on dimercaptosuccinic acid scan developed dysfunctional voiding only at a slightly greater, but not significantly different, rate than those with normal kidneys.

Female↗
PubMed2005

A multivariable assessment of renal size and growth of scarred kidneys in children.

PURPOSE: We applied a recently developed multivariable renal size nomogram to sonographic measurements of kidneys with known scarring to assess systematically their sizes and growth patterns compared to normal kidneys. MATERIALS AND METHODS: We retrospectively reviewed renal sonograms of 138 kidneys (55 right and 83 left) with known scarring. The sizes of these scarred kidneys were compared to the 95% prediction limits calculated according to the multivariable renal size nomogram, adjusting for patient age, gender, race, weight and height. The growth of scarred kidneys was evaluated by fitting individual linear regression lines using serial sonographic measurements and comparing the results with normal predicted values. RESULTS: The sizes of 89.1% of the right and 81.9% of the left scarred kidneys were within the 95% normal prediction limits. Only 17 of 138 of the scarred renal units showed smaller kidney sizes compared to the normal prediction limits. Serial sonographic measurements revealed that compared to normal predicted values, 24 of 60 left and 16 of 38 right scarred kidneys grew within +/- 1.0% annually of the boundaries of normal predicted values. Additionally, 8 left and 7 right scarred kidneys indicated a growth rate of more than 1% annually higher than the normal predicted values. CONCLUSIONS: Multivariable analyses of renal sonographic measurements provided a dynamic picture of kidney well-being in children with renal scarring. We found that the majority of scarred kidneys were within the normal predicted limits, and a large proportion of these kidneys grew equally well compared to those with normal anatomy.

Adolescent↗
PubMed2005

Endemic nephropathy: the case for chronic poisoning by aristolochia.

AIM: To explore the hypothesis that chronic dietary poisoning by aristolochic acid could account for the unique geographical distribution, specific pattern of tubulointerstitial fibrosis, occurrence of chronic renal insufficiency, and an increased risk of developing upper urothelial cancer, all of which are associated with endemic nephropathy. METHODS: This case-controlled epidemiologic study consisted of three groups of subjects residing in an endemic region of Croatia: (a) patients meeting WHO criteria for endemic nephropathy (n=28), (b) individuals who have been treated for renal insufficiency secondary to other forms of renal disease (n=30), and (c) apparently healthy residents of the endemic village (n= 30). A detailed questionnaire, designed to collect information on demographics, exposure to potentially toxic substances, diet, agricultural practices, and other factors potentially impacting endemic nephropathy was administered to the three study groups. The seeds of Aristolochia clematitis, obtained from plants growing in the endemic region, were extracted with ethanol and analyzed by high-performance liquid chromatography for their aristolochic acid content. RESULTS: The majority of subjects, including 90% of endemic nephropathy patients, recall that the plant Aristolochia clematitis (birthwort, vucja stopa in Croatian) was frequently found in local meadows and wheat fields between 20 and 30 years ago. At that time, endemic nephropathy patients encountered Aristolochia clematitis significantly more frequently than controls (P=0.035). Since then, all three study groups reported a significant increase in the use of herbicides (P<0.001) and reduction in the prevalence of Aristolochia clematitis (P<0.001). Chemical analysis established that the seeds of A. clematitis contain 0.65% aristolochic acid. It is likely that the harvesting process used by local farmers permitted the seeds of A. clematitis to mingle with the wheat grain. CONCLUSION: Flour used to bake bread, a dietary staple in the endemic region of Croatia, is derived from wheat grain which, in the past, is likely to have been contaminated with seeds of A. clematitis during harvesting. This observation supports the hypothesis that aristolochic acid, a major constituent of the seeds, plays a central role in the development of endemic nephropathy.

Aristolochia↗
PubMed2004

Impact of shared epitope genotype and ethnicity on erosive disease: a meta-analysis of 3,240 rheumatoid arthritis patients.

OBJECTIVE: The strongest known genetic association in rheumatoid arthritis (RA) is with HLA-DRB1 alleles that share a similar amino acid sequence, termed the shared epitope (SE). Although many studies have examined the association of the SE with disease severity, the results have been inconsistent, which may reflect the relatively small sample sizes or ethnic differences. The aim of this study was to assess the association of HLA-DRB1 SE alleles and genotype with the development of bony erosions in RA by meta-analysis. METHODS: We identified English-language articles published between January 1, 1987 and June 1, 1999 through Medline, EMBase, and manual searches of 6 relevant journals. Included were studies in which molecular typing of HLA-DRB1 alleles was performed and in which the presence or absence of bony erosions was reported. Data were extracted from the studies, and erosions were coded as present or absent. Authors were contacted for missing information and data on individual patients. RESULTS: A total of 29 studies and 3,240 patients were available for analysis. The summary odds ratios (ORs), when all patients were evaluated as a single group, demonstrated a significant association of the presence of the SE (2 or 1 versus 0 SE alleles) with erosions (OR 2.0; 95% confidence interval [95% CI] 1.8-2.2), although significant heterogeneity was present (P = 0.002). Subgroup analyses demonstrated the important influence of ethnic background. For example, no association of the SE with erosions was demonstrated in Greeks (OR 0.8 [95% CI 0.2-1.5]). In contrast, there was a striking dose-dependent relationship in southern European Caucasians and Asians, with ORs as high as 6.2 and 5.4, respectively, in patients with 2 SE alleles. Although our ability to assess the relationship between SE genotype and erosions was limited, particular importance of the DRB1*0401 SE allele was suggested in an analysis restricted to northern European Caucasians. CONCLUSION: The SE is associated with the development of erosive disease in many ethnic groups; however, striking exceptions exist. These variations may be due to allele differences between populations, such as the frequency of DRB1*0401 among different ethnic groups. Further study to better understand the genetic and environmental differences between these populations may provide insight into mechanisms that influence the clinical expression of RA.

Arthritis, Rheumatoid↗
PubMed2004

A multivariate analysis of dysfunctional elimination syndrome, and its relationships with gender, urinary tract infection and vesicoureteral reflux in children.

PURPOSE: We explored and quantified the relationships between dysfunctional elimination syndrome (DES), and gender, urinary tract infection (UTI) and vesicoureteral reflux (VUR) in children. MATERIALS AND METHODS: Data on 2,759 pediatric patients treated at a referral practice who underwent renal sonography and voiding cystourethrography were summarized. The patients were children with VUR or normal genitourinary anatomy who presented with UTI or dysfunctional voiding and children screened for genitourinary problems such as hematuria, sibling reflux or bedwetting. A multivariate logistic regression approach was used to model and quantify the associations between DES and other pediatric urology factors. RESULTS: Of the girls 36.0% with unilateral VUR had DES, while 36.1% with bilateral VUR had DES. The corresponding rates for boys were 20.5% and 21.2%. The higher rate of DES in girls was independent of UTI and VUR status. While UTI was not associated with DES in boys or girls without VUR, in patients with VUR and UTI the risk of DES almost doubled (OR 1.97). Reflux alone without UTI was negatively associated with DES in boys (OR 0.50, 95% CI 0.34, 0.73) and girls (OR 0.26, 95% CI 0.19, 0.36). CONCLUSIONS: Girls had a significantly higher rate of DES than boys in all UTI and VUR subgroups in the current data. UTI significantly impacts the DES occurrence in patients with VUR. No statistically significant difference was detected in the DES rate between the unilateral and bilateral VUR groups, and the reflux group as a whole did not seem to have a higher rate of DES in boys or girls.

Child↗
PubMed2004

Effectiveness of individually tailored calendars in promoting childhood immunization in urban public health centers.

OBJECTIVES: We examined the effectiveness of tailored calendars in increasing childhood immunization rates. METHODS: Parents of babies aged birth to 1 year (n = 321) received individually tailored calendars promoting immunization from 2 urban public health centers. For each baby, an age- and sex-matched control was selected from the same center. Immunization status was tracked through age 24 months. RESULTS: A higher proportion of intervention than of control babies were up to date at the end of a 9-month enrollment period (82% vs 65%, P <.001) and at age 24 months (66% vs 47%, P <.001). The younger the baby's age at enrollment in the program, the greater was the intervention effect. CONCLUSIONS: Tailored immunization calendars can help increase child immunization rates.

Black or African American↗
PubMed2004

Effectiveness of cleaning and health education in reducing childhood lead poisoning among children residing near superfund sites in Missouri.

In this study, the authors evaluated whether a combination of tailored education, lead dust removal by trained cleaning specialists, and family follow-up visits would be more effective than conventional health educational programs in reducing elevated blood lead levels in children living in or near lead mining hazardous waste sites. The authors randomized children between 6 and 72 mo of age with blood lead levels between 10 and 20 microg/dl into 3 groups: standard care, tailored newsletters, or tailored newsletters and specialized cleaning. The authors obtained questionnaires, blood lead levels, and environmental lead samples during initiation and compared them with the same items obtained at 3, 6, and 9 mo follow-up. They used a linear mixed effect model to evaluate the intervention effect. Blood lead levels decreased overall 1.54 microg/dl (12.1%) during the study. The authors found that tailored newsletters and specialized cleaning produced the greatest decline in blood lead levels, but no statistical differences were found among the methodologies. The small decline observed in blood lead levels reduced levels to below 10 microg/dl for 40% of the children.

Child↗
PubMed2003

Infant vesicoureteral reflux: a comparison between patients presenting with a prenatal diagnosis and those presenting with a urinary tract infection.

OBJECTIVES: To evaluate the severity, laterality, and gender distribution of infant vesicoureteral reflux (VUR) and its potential impact on renal outcome, we compared patients presenting fetally (FDR group) and those presenting with a urinary tract infection (INF group). METHODS: A retrospective review of 202 patients with the diagnosis of VUR before 6 months of age was performed. The grade of VUR, gender, laterality, initial renal scarring, breakthrough urinary tract infections, new renal scarring, and surgical intervention were compared between the INF group (n = 146) and FDR group (n = 56). RESULTS: The male/female ratio in the FDR group was 1.67:1 compared with 0.60:1 in the INF group. The FDR group had more unilateral VUR than the INF group (P <0.001), and no significant difference was found between the two groups in terms of VUR grade distribution (P = 0.13), percentage of initial damage (28% of FDR patients versus 23% of INF patients), or clinical course. In either group, boys and girls exhibited a very similar distribution of grade and renal damage. CONCLUSIONS: Our findings do not support the commonly held belief that fetally diagnosed reflux is an overwhelmingly male, bilateral, and high-grade phenomenon. Few differences were observed between infants diagnosed fetally and those diagnosed subsequent to urinary tract infection. Once diagnosed, from either group, infant reflux has neither great morbidity nor a frequent need for surgery.

Age Factors↗
PubMed2003

The role of repeat victimization in adolescent delinquent behaviors and recidivism.

PURPOSE: To report prevalence of adolescent victimization and delinquency recidivism as well as to assess the association between repeat victimization and delinquency recidivism in a large, population-based sample of high school seniors. METHODS: A nationally representative sample of the Monitoring the Future Project (about 17,000 high school seniors from 1996 to 1999) was analyzed as a pooled sample. The analysis was based on self-reported measures of ten different types of delinquent behaviors including violent and property offenses. Other measures included in the analysis are victimization and information about sociodemographic (e.g,. geographic region, parental education, number of parents in the home) and lifestyle (e.g., grade from average, truancy, work experience, religious commitment) characteristics. Pairwise and multivariate methods were used to examine the risk association between repeat victimization and delinquency recidivism. RESULTS: From 1996 to 1999, a downward trend was observed for most types of delinquent behaviors: recidivism among seniors except for hitting instructors/supervisors, damaging school property, and car theft. For the same study period, the prevalence of victimization recidivism was also on the decline except for injury with a weapon and physical threats. Repeat victimization was found to be significantly associated with delinquency recidivism. Other risk factors more frequently associated with delinquency recidivism included gender, race, drug use, poor school performance, truancy, risk-seeking, and conflicts with parents. CONCLUSIONS: The present study showed a significant association between repeat victimization and delinquent recidivism; it identified characteristics of adolescent at risk of repetitive delinquent behaviors, which could be used for planning intervention strategies.

Adolescent↗
PubMed2003

Infection control practitioners' perceptions and educational needs regarding bioterrorism: results from a national needs assessment survey.

BACKGROUND: The perceived threat that biological weapons will be used in an act of terror against the United States has escalated sharply since the discovery of anthrax-tainted letters after the terrorist attacks of September 11, 2001. These events underscore the critical nature of health care and public health preparedness and the need to augment infection control practitioner education and training. METHODS: Between October 2000 and August 2001 a national needs assessment was conducted by use of a 35-question survey. The survey measured infection control practitioners' (ICPs') perception of the risk for bioterrorism in the United States and in their community, the proportion of ICPs with prior training in bioterrorism preparedness, and preferences for delivery media of future bioterrorism education. RESULTS: The assessment of the perceived threat of bioterrorism in the United States during the next 5 years (P =.022) and in the ICPs' work community (P <.001) revealed significant regional differences. Only half (56%) of the respondents reported prior training in bioterrorism preparedness. Respondents reported that the 2 most common barriers to receiving training were lack of training opportunities (70.2%) or no dedicated work time for training (19.4%). CONCLUSIONS: The results of this study indicate an urgent need for more resources and opportunities for clinical education in bioterrorism preparedness that will provide continuing education credit. Successful bioterrorism education will require a variety of instructional designs and media delivery methods to address ICPs' preferences and needs.

Bioterrorism↗
PubMed2003

The accuracy of predicting cardiac arrest by emergency medical services dispatchers: the calling party effect.

OBJECTIVES: To analyze the accuracy of paramedic emergency medical services (EMS) dispatchers in predicting cardiac arrest and to assess the effect of the caller party on dispatcher accuracy in an advanced life support, public utility model EMS system, with greater than 90,000 calls and greater than 60,000 transports per year. METHODS: This was a retrospective analysis from January 1, 2000, through June 30, 2000, of 911 calls with dispatcher-assigned presumptive patient condition (PPC) or field diagnosis of cardiac arrest. Sensitivity and positive predictive value (PPV) of the PPC code for cardiac arrest by calling parties were calculated. Homogeneity of sensitivity and PPV of the PPC code for cardiac arrest by calling parties was studied with chi-square analysis. Relevant proportions, relative risk ratios, and associated 95% confidence intervals (95% CIs) were calculated. Student's t-test was used to compare quality assurance scores between calling parties. RESULTS: There were 506 patients included in the study. Overall sensitivity for dispatcher-assigned PPC of cardiac arrest was 68.3% (95% CI = 63.3% to 73.0%) with a PPV of 65.0% (95% CI = 60.0% to 69.7%). There was a significant difference in the PPV for the EMS dispatcher diagnosis of cardiac arrest depending on the type of caller (chi(2) = 17.34, p < 0.001). CONCLUSIONS: A higher level of medical training may improve dispatch accuracy for predicting cardiac arrest. The type of calling party influenced the PPV of dispatcher-assigned condition.

Emergency Medical Services↗